Reflection type screen and video display device

Abstract

To provide a reflection type screen that can display a clear video with high contrast, and a video display device including the same.SOLUTION: A screen 70 is a reflection type screen, and comprises: a semi-transmissive reflection layer 13 that has a fine and irregular rugged shape formed on a surface, diffuses and reflects at least part of light incident thereon with the rugged shape, and transmits part of the light; and a light control layer 30 that is arranged closer to the back than the reflection layer 13 in a thickness direction of the screen 70 from the reflection layer 13, and can absorb part of light incident thereto and transmit part of the light to adjust transmissivity. The screen does not include a light diffusion layer containing particles for diffusing light.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a reflective screen and an image display device including the same. [Background technology]

[0002] Conventionally, various types of reflective screens have been developed that display images by reflecting image light projected from an image source. Among them, for example, a transparent reflective screen (see, for example, Patent Document 1) can be fixed by, for example, attaching it to a highly translucent member such as window glass, and can display images by reflecting the projected image light. Furthermore, when the screen is not in use and no image light is projected, the scenery on the other side of the screen can be observed through the screen, and therefore demand for such a screen is increasing due to its high designability. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-156452 Summary of the Invention [Problem to be solved by the invention]

[0004] In transparent reflective screens, part of the image light passes through the reflective layer and is totally reflected at the interface on the back side of the screen before being emitted toward the image source, which can cause image blurring such as double images and reduce the clarity of the image. Furthermore, in a transparent reflective screen, the black luminance of the image tends to be high, which also poses a problem of reduced image contrast.

[0005] An object of the present invention is to provide a reflective screen capable of displaying clear images with high contrast, and an image display device including the same. [Means for solving the problem]

[0006] The present invention solves the above-mentioned problems by the following means: For ease of understanding, the following description will be given with reference to the corresponding embodiments of the present invention, but the present invention is not limited to these. The first invention is a reflective screen (70, 20, 40, 80) that displays an image by reflecting at least a portion of the image light projected from an image source, and is characterized by comprising: a semi-transparent reflective layer (13) having fine, irregular unevenness formed on the surface, which diffuses and reflects at least a portion of the incident light by the unevenness and transmits a portion of it; and a dimming layer (30) that is arranged behind the reflective layer in the thickness direction of the reflective screen, and absorbs a portion of the incident light and transmits a portion of it, making it possible to adjust the transmittance; and the reflective screen (70, 20, 40, 80) does not have a light diffusion layer containing particles that diffuse light. The second invention is a reflective screen (70, 20, 40, 80) characterized in that, in the reflective screen of the first invention, the light-controlling layer (30) comprises a layer (36) containing a liquid crystal material containing a dichroic dye. The third invention is a reflective screen (70, 20, 40, 80) according to the first or second invention, characterized in that the light-controlling layer (30) has a higher light absorptance for light with an incident angle of 40° or more than the absorptance for light with an incident angle of 0° when the light transmittance is high. The fourth invention is a reflective screen (70, 20, 40, 80) that is a reflective screen of any of the first to third inventions, comprising: a first optical shape layer (12) having a first surface (121a) on which image light is incident and a second surface (121b) intersecting the first surface (121a) and in which a plurality of unit optical shapes (121) that are convex on the back side are arranged; and a second optical shape layer (14) that is provided adjacent to the reflective layer on the back side of the reflective layer (13), has optical transparency, and is laminated so as to fill in valleys formed by adjacent unit optical shapes, wherein the reflective layer is formed on at least a part of the first surface of the unit optical shapes, and the surface of the second optical shape layer on the back side is flat and has a refractive index equal to that of the first optical shape layer or a refractive index difference that is small enough to be considered equal. The fifth invention is a reflective screen (70, 20, 40, 80) characterized in that, in the reflective screen of the fourth invention, the first optical shape layer (12) has a Fresnel lens shape on the back side, and the unit optical shapes are arc-shaped when viewed from a direction perpendicular to the screen surface, and are arranged concentrically around a point (C) located outside the display area of the reflective screen. The sixth invention is a reflective screen (80) characterized in that, in the reflective screen of any one of the first to fifth inventions, the light-controlling layer (30) has a highly light-transmitting substrate layer laminated on the image source side or the back side, or is sandwiched between two highly light-transmitting substrate layers (88, 89) in the thickness direction. The seventh invention is a reflective screen (20, 40) characterized in that, in any of the reflective screens of the first to sixth inventions, it is provided with a light control layer (16) that is located closer to the image source than the reflective layer (13) in the thickness direction of the reflective screen, diffuses and transmits light incident from a specific angle range (R1), and transmits light incident from outside the specific angle range without diffusing it. An eighth invention is an image display device (7) comprising a reflective screen (70, 20, 40, 80) according to any one of the first to seventh inventions, and an image source (LS) that projects image light onto the reflective screen. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a reflective screen capable of displaying clear images with high contrast, and an image display device including the same. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 2 is a diagram showing a video display device 7 according to the first embodiment. [Figure 2] FIG. 2 is a diagram showing a layer structure of the screen 70 of the first embodiment. [Figure 3] FIG. 2 is a diagram illustrating a first optical shape layer 12. [Figure 4]10 is a diagram showing the orientation of the liquid crystal material in the light-switching layer 30. FIG. [Figure 5] FIG. 1 is a diagram illustrating a method for measuring the change in transmittance depending on the angle of incidence in Samples 1 to 3. [Figure 6] 1 is a graph showing the rate of decrease in transmittance for obliquely incident light relative to the front transmittance for Samples 1 to 3. [Figure 7] 3A and 3B are diagrams illustrating an example of image light and external light incident on the screen 70 of the first embodiment. [Figure 8] FIG. 10 is a diagram showing a layer structure of a screen 20 according to a second embodiment. [Figure 9] 3A and 3B are diagrams illustrating the light control effect of the light control layer 16. FIG. [Figure 10] 10A and 10B are diagrams illustrating an example of image light and external light incident on a screen 20 according to a second embodiment. [Figure 11] FIG. 10 is a diagram showing a layer structure of a screen 40 according to a third embodiment. [Figure 12] FIG. 10 is a diagram showing a layer structure of a screen 80 according to a fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described with reference to the drawings, etc. Note that the drawings shown below, including Fig. 1, are schematic diagrams, and the size and shape of each part are appropriately exaggerated to facilitate understanding. In this specification, terms specifying shapes or geometric conditions, such as parallel and orthogonal, are intended to include not only their strict meanings but also states that perform similar optical functions and have an error that can be considered as parallel or orthogonal.

[0010] Furthermore, in this specification, the terms plate, sheet, film, etc. are used, but in general, these are used in order of thickness, that is, plate, sheet, film, and so on, and this specification follows suit. However, since there is no technical significance in this distinction, these terms can be used interchangeably as appropriate. Furthermore, the numerical values such as dimensions of each member and the names of materials described in this specification are examples of embodiments, and are not limited to these and can be selected as appropriate.

[0011] (First embodiment) Fig. 1 is a diagram showing an image display device 7 according to a first embodiment. Fig. 1(a) is a perspective view of the image display device 7, and Fig. 1(b) is a view of the image display device 7 as seen from the side (the +X side, which will be described later). The image display device 7 includes a screen 70, an image source LS, etc. The screen 70 is a reflective screen that reflects a portion of the image light L0 projected from the image source LS to display an image on the screen. Details of the screen 70 will be described later.

[0012] For ease of understanding, an XYZ Cartesian coordinate system is provided as appropriate in each of the following figures, including Fig. 1. In this coordinate system, the horizontal direction (left-right direction) of the screen of screen 70 is the X direction, the vertical direction (up-down direction) is the Y direction, and the thickness direction of screen 70 is the Z direction. The screen of screen 70 is parallel to the XY plane, and the thickness direction of screen 70 (Z direction) is perpendicular to the screen of screen 70. Furthermore, the direction toward the right in the horizontal direction as viewed from an observer O1 positioned directly in front of the image source side of the screen 70 is the +X direction, the direction toward the upper vertical direction is the +Y direction, and the direction from the back side (rear side) toward the image source side in the thickness direction is the +Z direction. Furthermore, in the following description, unless otherwise specified, the up-down direction, left-right direction, and thickness direction of the screen refer to the up-down direction (vertical direction), left-right direction (horizontal direction), and thickness direction (depth direction) of the screen when this screen 70 is in use, and are assumed to be parallel to the Y direction, X direction, and Z direction, respectively.

[0013] The image source LS is an image projection device that projects image light L0 onto the screen 70, and is, for example, a short-focus projector. In this embodiment, the image source LS is a DLP projector that uses a high-pressure mercury lamp as a light source. However, the image source is not limited to this, and an image source that uses another light source such as a laser or an LED may be used depending on the desired optical performance, the environment in which the image display device 1 is used, and the like. When the image display device 7 is in use, this image source LS is located in the center of the screen 70 in the left-right direction and vertically below the screen of the screen 70 when the screen (display area) of the screen 70 is viewed from the front (normal direction of the screen surface). In this specification, the screen surface refers to the plane of the screen when viewed as a whole. The screen surface of the screen 70 is parallel to the image plane (XY plane) of the screen 70.

[0014] The image source LS can project the image light L0 obliquely from a position in the depth direction (Z direction) that is much closer to the surface of the screen 70 than a general-purpose projector that is positioned directly in front of the screen of a conventional screen. Therefore, compared to a conventional general-purpose projector, the image source LS has a shorter projection distance to the screen 70, a larger incident angle at which the projected image light L0 is incident on the screen 70, and a larger amount of change in the incident angle (amount of change from minimum to maximum).

[0015] The screen 70 is a semi-transparent reflective screen that reflects a portion of the image light L0 projected by the image source LS toward an observer O1 positioned in front of the image source (+Z side), displaying an image to the observer O1, and transmits a portion of the light. The screen 70 is transparent, allowing the observer O1 to view the scenery on the other side (-Z side) through the screen 70. When in use, the screen (display area) of the screen 70 is a substantially rectangular shape with its longer sides aligned horizontally as viewed from the observer O1 side. The screen 70 has a diagonal screen size of approximately 40 to 100 inches and an aspect ratio of 16:9. However, without being limited to this, the screen 70 may have a different shape when viewed from the observer O1 side, and the screen size may be 40 inches or less, and the size and shape can be selected appropriately depending on the purpose of use, the environment in which it is used, etc.

[0016] The screen 70 of this embodiment is integrally joined (or partially fixed) to a support plate (not shown) on the rear side via a joining layer (not shown), thereby maintaining the flatness of the screen. The support plate is a rigid, flat member, and can be made of a resin such as an acrylic resin or a PC (polycarbonate) resin, or a plate-like member made of glass, etc. In addition, when the screen 70 is transparent as in this embodiment, it is preferable that the support plate also be transparent. However, the screen 70 is not limited to this, and may have a configuration in which its four sides are supported by a frame member (not shown) or the like, thereby maintaining its flatness. The image display device 7 of this embodiment can be applied to indoor partitions, image displays at exhibitions, and shop windows, and the like, and the support plate can be selected appropriately depending on the intended use.

[0017] Fig. 2 is a diagram showing the layer structure of the screen 70 of the first embodiment. Fig. 2 shows an enlarged portion of a cross section that passes through point A (see Fig. 1) which is the center of the screen (the geometric center of the screen) of the screen 70, is parallel to the vertical direction of the screen (Y direction), and is perpendicular to the screen surface (parallel to the Z direction). Fig. 3 is a diagram illustrating the first optical shape layer 12. Fig. 3 is a diagram illustrating the first optical shape layer 12 as viewed from the back side (-Z side), and for ease of understanding, the reflective layer 13 and the like are omitted. As shown in Figure 2, the screen 70 has, in the thickness direction (Z direction), in order from its image source side (+Z side), a first base material layer 11, a first optical shape layer 12, a reflective layer 13, a second optical shape layer 14, a second base material layer 15, a bonding layer 17c, a dimming layer 30, etc.

[0018] The first base material layer 11 is a sheet-like member having optical transparency, and the first optical shape layer 12 is integrally formed on the back side (-Z side) of the first base material layer 11. This first base material layer 11 is a layer that serves as a base material (base) for forming the first optical shape layer 12. The first base layer 11 is formed from, for example, a polyester resin such as PET (polyethylene terephthalate) having high light transmittance, an acrylic resin, a styrene resin, an acrylic-styrene resin, a PC (polycarbonate) resin, an alicyclic polyolefin resin, a TAC (triacetyl cellulose) resin, or the like.

[0019] The first optical shape layer 12 is a light-transmitting layer formed on the back side (-Z side) of the first base layer 11. A plurality of unit optical shapes (unit lenses) 121 are arranged on the back side (-Z side) surface of the first optical shape layer 12. 3, the unit optical shape 121 has a partial shape (arc shape) of a perfect circle, and a plurality of unit optical shapes 121 are arranged concentrically around a point C located outside the image plane (display area) of the screen 70. That is, the first optical shape layer 12 has, on its back surface side, a circular Fresnel lens shape with an offset structure, with the point C as its center (Fresnel center). In this embodiment, as shown in Figure 3, when the first optical shape layer 12 is viewed from the back side (-Z side) along the normal direction of the screen surface, point C is located in the center of the screen in the left-right direction and below the outside of the screen, and point C and point A are located on the same straight line extending in the Y direction.

[0020] As shown in FIG. 2, the unit optical shapes 121 are parallel to the direction (Z direction) perpendicular to the screen surface, and the cross section parallel to the arrangement direction of the unit optical shapes 121 has a substantially triangular shape. Each unit optical shape 121 is convex on the rear side (-Z side), and has a first slope (lens surface) 121a onto which image light is incident and a second slope (non-lens surface) 121b intersecting the first slope 121a. In each unit optical shape 121, the first slope 121a is located above the second slope 121b (+Y side), with the vertex t1 in between. The angle between the first inclined surface 121a and a plane parallel to the screen surface (XY plane) is α. The angle between the second inclined surface 121b and a plane parallel to the screen surface is β. The angles α and β satisfy the relationship β>α.

[0021] Furthermore, a minute and irregular uneven shape is formed on the first inclined surface 121a and the second inclined surface 121b of the unit optical shape 121. This uneven shape is formed by irregularly arranging convex shapes and concave shapes in two dimensions, and the convex shapes and concave shapes are irregular in size, shape, height, etc.

[0022] The arrangement pitch of the unit optical shapes 121 is P, and the height of the unit optical shapes 121 (the dimension from the vertex t1 in the thickness direction to the point t2 that is the bottom between the unit optical shapes 121) is h. For ease of understanding, in Fig. 2 and other figures, the arrangement pitch P and angles α and β of the unit optical shapes 121 are shown as being constant in the arrangement direction of the unit optical shapes 121. However, in reality, the arrangement pitch P of the unit optical shapes 121 of this embodiment is constant, but the angle α gradually (continuously) increases as it moves away from point C, which is the Fresnel center, in the arrangement direction of the unit optical shapes 121 (as it moves upward in the cross section shown in Fig. 2).

[0023] However, without being limited to this, for example, the arrangement pitch P may be gradually changed along the arrangement direction of the unit optical shapes 121, or the arrangement pitch P, angle α, etc. may be changed in stages along the arrangement direction of the unit optical shapes 121. The angles α, β, array pitch P, etc. may be set appropriately depending on the projection angle of the image light from the image source LS (the incident angle of the image light onto the screen 70), the size of the pixels of the image source LS, the screen size of the screen 70, the refractive index of each layer, etc.

[0024] In the present embodiment, an example has been shown in which a circular Fresnel lens shape is formed on the surface on the rear side (-Z side) of the first optical shape layer 12, but the present invention is not limited to this, and a linear Fresnel lens shape in which unit optical shapes 121 extend in the left-right direction of the screen (X direction) and are arranged in the up-down direction of the screen (Y direction) may be formed on the surface on the rear side of the first optical shape layer 12. Also, a plurality of unit prisms, each having a substantially triangular cross section and extending with its ridge line in the left-right direction of the screen (X direction), may be arranged in the up-down direction of the screen (Y direction).

[0025] The first optical shape layer 12 is formed of an ultraviolet curable resin having high light transmittance, such as a urethane acrylate, polyester acrylate, epoxy acrylate, polyether acrylate, polythiol, or butadiene acrylate. In this embodiment, the resin constituting the first optical shape layer 12 is described using an ultraviolet curable resin as an example, but this is not limited to this, and the layer may be formed from other ionizing radiation curable resins such as electron beam curable resins.

[0026] The reflective layer 13 is a semi-transmissive reflective layer that reflects part of incident light and transmits part of it, and is a so-called half mirror. The reflective layer 13 is formed on the unit optical shape 121, i.e., on the first inclined surface 121a and the second inclined surface 121b. The reflective layer 13 is provided between and adjacent to the first optical shape layer 12 and the second optical shape layer 14. The reflective layer 13 has a rough surface with fine irregular concave-convex shapes on its image source side surface (surface on the first optical shape layer 12 side) and back side surface (surface on the second optical shape layer 14 side). This is because, as described above, the first inclined surface 121a and the second inclined surface 121b have fine concave-convex shapes formed thereon, the reflective layer 13 is formed to follow these fine concave-convex shapes, and the thickness of the reflective layer 13 is sufficiently thinner than the concave-convex shapes of these fine concave-convex shapes. The reflective layer 13 has the function of diffusing and reflecting part of the incident light by means of the fine irregular uneven shape, and transmitting at least part of the remaining light that is not reflected without diffusing it.

[0027] The reflectance and transmittance of the reflective layer 13 can be appropriately set according to the desired optical performance. From the viewpoint of favorably reflecting the image light and favorably transmitting light other than the image light (for example, light from the outside world such as sunlight), the reflectance and transmittance of the reflective layer 13 are preferably about 30 to 80% for transmittance and about 5 to 60% for reflectance.

[0028] The reflective layer 13 is formed of a metal having high light reflectivity, such as aluminum, silver, nickel, chromium, etc. The reflective layer 13 is not limited to this, and may be formed, for example, by sputtering the above-mentioned metal having high light reflectivity, transferring a metal foil, or applying paint containing a metal thin film. The reflective layer 13 may also be formed by vapor deposition of a dielectric multilayer film or a dielectric single layer film that has high transparency, small light absorption loss, and can achieve high reflectance. The reflective layer 13 of this embodiment is formed by vapor deposition of chromium, and the reflective layer 13 alone has a reflectance of about 5% and a transmittance of about 50%. In this embodiment, an example has been shown in which the reflective layer 13 is formed on the first inclined surface 121a and the second inclined surface 121b of the unit optical shape 121, but this is not limited to this, and the reflective layer 13 may be formed on at least a part of the first inclined surface 121a, for example.

[0029] The second optical shape layer 14 is a light-transmitting layer provided adjacent to the back side (-Z side) of the reflective layer 13. The second optical shape layer 14 is filled so as to sufficiently fill the valleys between adjacent unit optical shapes 121, and the surface on the back side of the second optical shape layer 14 is a flat surface parallel to the screen surface. Such a second optical shape layer 14 improves the light transmittance of the screen 70 and can protect the reflective layer 13. Furthermore, by providing the second optical shape layer 14, it becomes easier to laminate the second base material layer 15 and the light control layer 30.

[0030] From the viewpoint of improving the transparency of the screen 70, it is preferable that the refractive index of the second optical shape layer 14 is equal to that of the first optical shape layer 12, or that the difference in refractive index is small enough to be considered equal. Furthermore, the second optical shape layer 14 may be formed using the same resin as that of the first optical shape layer 12, or may be formed using a different resin. The second optical shape layer 14 of this embodiment is formed from the same ultraviolet curable resin as the first optical shape layer 12, and has the same refractive index as the first optical shape layer 12.

[0031] The second base material layer 15 is a sheet-like member having optical transparency, and is laminated integrally on the back surface side of the second optical shape layer 14. Like the first base material layer 11, the second base material layer 15 is formed from, for example, a polyester resin such as PET (polyethylene terephthalate) having high optical transparency, an acrylic resin, a styrene resin, an acrylic-styrene resin, a PC (polycarbonate) resin, an alicyclic polyolefin resin, or a TAC (triacetyl cellulose) resin. In this embodiment, the second base material layer 15 is made of the same material as the first base material layer 11 and has the same refractive index as the first base material layer 11.

[0032] The bonding layer 17c is a layer that functions to integrally bond the second base material layer 15 and the light-controlling layer 30. The bonding layer 17c can be made of an adhesive or sticky material with high light transparency.

[0033] The light-controlling layer 30 is a film that can control the amount of transmitted light by changing the applied voltage, and has the function of absorbing at least a portion of the incident light and controlling the amount of transmitted light. The light-controlling layer 30 is a guest-host type liquid crystal cell that uses a dichroic dye and changes the amount of light transmitted by an electric field applied to the liquid crystal. The light-controlling layer 30 is configured by sandwiching a liquid crystal layer 36 between a film-like second liquid crystal laminate 30B and a film-like first liquid crystal laminate 30A. The second laminate for liquid crystal 30B is formed by laminating a transparent electrode 32B, an alignment layer 33B, and bead spacers 34 on a substrate 31B. The first laminate for liquid crystal 30A is formed by laminating a transparent electrode 32A and an alignment layer 33A on a substrate 31A. The dimming layer 30 changes the orientation of the liquid crystal material made of a guest-host liquid crystal composition provided in the liquid crystal layer 36 by driving the transparent electrodes 32A, 32B provided in the first liquid crystal laminate 30A and the second liquid crystal laminate 30B, thereby changing the amount of transmitted light.

[0034] Various transparent resin films can be used for the substrates 31A and 31B, but it is preferable to use a transparent resin film that has small optical anisotropy and a transmittance of 80% or more in the visible wavelength range (380 to 800 nm). Examples of materials for transparent resin films include acetylcellulose-based resins such as triacetylcellulose (TAC), polyester-based resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyolefin-based resins such as polyethylene (PE), polypropylene (PP), polystyrene, polymethylpentene, and EVA, vinyl-based resins such as polyvinyl chloride and polyvinylidene chloride, acrylic resins, polyurethane-based resins, polysulfone (PEF), polyethersulfone (PES), polycarbonate (PC), polysulfone, polyether (PE), polyether ketone (PEK), (meth)acrylonitrile, cycloolefin polymer (COP), and cycloolefin copolymer. As the material for the transparent resin film, resins such as polycarbonate (PC), cycloolefin polymer (COP), and polyethylene terephthalate (PET) are particularly preferred. The substrates 31A and 31B can be made of transparent resin films of various thicknesses.

[0035] The transparent electrode (first electrode) 32A and the transparent electrode (second electrode) 32B are made of a transparent conductive film laminated on a transparent resin film. The transparent conductive film can be made of various transparent electrode materials that are used for this type of transparent resin film, including oxide-based transparent metal thin films with a total light transmittance of 50% or more, such as tin oxide, indium oxide, and zinc oxide.

[0036] Examples of tin oxide (SnO2) based materials include NESA (tin oxide SnO2), ATO (antimony tin oxide: antimony-doped tin oxide), and fluorine-doped tin oxide. Examples of indium oxide (In2O3) based materials include indium oxide, ITO (Indium Tin Oxide), and IZO (Indium Zinc Oxide). Zinc oxide (ZnO) based materials include zinc oxide, AZO (aluminum-doped zinc oxide), and gallium-doped zinc oxide. In this embodiment, the transparent conductive film is made of ITO (Indium Tin Oxide).

[0037] In this embodiment, spherical bead spacers 34 are used as the spacers. The bead spacers 34 are provided to define the thickness (cell gap) of the liquid crystal layer 36 excluding the outer periphery. The bead spacers 34 can be made of a wide variety of materials, including inorganic materials such as silica, organic materials, and core-shell structures that combine these materials. In addition to the spherical shape described above, the bead spacers 34 may also be rod-shaped, such as cylindrical or prismatic. However, the spacers that determine the thickness of the liquid crystal layer 36 are not limited to the bead spacers 34, and may be formed into a cylindrical shape, for example, by applying photoresist to the substrate 31A or the substrate 31B, exposing it to light, and developing it. In the above explanation, an example has been shown in which the spacers are provided in the second laminate for liquid crystal 30B, but this is not limited to this, and the spacers may be provided in both the first laminate for liquid crystal 30A and the second laminate for liquid crystal 30B, or only in the first laminate for liquid crystal 30A.

[0038] The alignment layers 33A and 33B are films for aligning liquid crystal molecules in a certain direction. For example, the alignment layers 33A and 33B may be in the form of alignment films themselves, or may be prepared by performing alignment treatment such as photo-alignment treatment or rubbing treatment, or by forming fine linear concave and convex shapes into the alignment layers. The method for preparing the alignment layers 33A and 33B is not limited to the above-described method, and other suitable methods may be used. In this embodiment, rubbing polyimide resin layers are used as the alignment layers 33A and 33B. Furthermore, in this embodiment, the light-switching layer 30 is shown to include the alignment layers 33A and 33B, but is not limited to this, and may be configured not to include the alignment layers 33A and 33B.

[0039] A wide variety of guest-host liquid crystal compositions using a dichroic dye composition can be used for the liquid crystal layer (liquid crystal material as a light-adjusting material) 36. The guest-host liquid crystal composition may contain a chiral agent, so that when the liquid crystal material is horizontally aligned (aligned parallel to the planar direction of the light-adjusting layer 30 and perpendicular to the thickness direction of the liquid crystal layer 36), it is oriented in a helical shape in the thickness direction of the liquid crystal layer 36. A sealant 35 is disposed in the light-adjusting layer 30 so as to surround the liquid crystal layer 36. This sealant 35 holds the first liquid crystal laminate 30A and the second liquid crystal laminate 30B together and prevents leakage of the liquid crystal material. The sealant 35 can be, for example, a thermosetting resin such as an epoxy resin or an acrylic resin, or a UV-curable resin.

[0040] The dimming layer 30 is configured as a normally dark layer by configuring the alignment layers 33B and 33A as horizontal alignment layers in which an alignment control force related to the pretilt is set in a certain direction so that the alignment of the guest-host liquid crystal composition when light is blocked is formed when no electric field is present. Here, "normally dark" refers to a structure in which transmittance is minimized when no voltage is applied to the liquid crystal, resulting in a black screen. "Normally clear" refers to a structure in which transmittance is maximized when no voltage is applied to the liquid crystal, resulting in a transparent screen. The light-blocking layer 30 may be configured as a normally clear layer, so that the orientation during light blocking is formed when an electric field is applied.

[0041] Fig. 4 is a diagram showing the orientation of the liquid crystal material in the light-controlling layer 30. For ease of understanding, Fig. 4 shows only the transparent electrodes 32A and 32B, the orientation layers 33A and 33B, and the liquid crystal material (liquid crystal composition 36a and dichroic dye 36b), with Fig. 4(a) showing the state when light is blocked (no voltage applied) and Fig. 4(b) showing the state when light is transmitted (voltage applied). 4(a), when no voltage is applied (when no electric field is present), the liquid crystal composition 36a and the dichroic dye 36b are horizontally aligned in one direction, i.e., the long axes of the liquid crystal composition 36a and the dichroic dye 36b are aligned in one direction, parallel to the transparent electrodes 32A and 32B and the alignment layers 33A and 33B (the so-called horizontal direction). In this state, most of the light incident on the light switchable layer 30 (light La and Lb shown in FIG. 4(a)) is absorbed by the dichroic dye 36b regardless of the angle of incidence, resulting in a light-blocking state in which the transmittance is minimized.

[0042] 4(b), when a voltage is applied (when an electric field is applied), the liquid crystal composition 36a and the dichroic dye 36b are aligned vertically in one direction, i.e., the long axes of the liquid crystal composition 36a and the dichroic dye 36b are aligned in one direction, perpendicular to the transparent electrodes 32A, 32B and the alignment layers 33A, 33B (the so-called vertical direction). In this state, light La incident on the light switchable layer 30 at a small incident angle, such as an incident angle of 0° or close to 0°, is transmitted through the liquid crystal layer 36 (the light switchable layer 30). However, as the incident angle increases, the light absorption rate by the dichroic dye increases. Therefore, most of the light Lb incident on the light switchable layer 30 at a large incident angle from an oblique direction is absorbed by the dichroic dye 36b, resulting in a significant decrease in transmittance. In other words, when a voltage is applied (when an electric field is applied), the light-controlling layer 30 has a higher absorptance for light incident at a large incident angle than for light incident at a small incident angle, such as an incident angle of 0° or close to 0°. Therefore, when a voltage is applied, the switchable layer 30 has high transmittance for light in a direction parallel to its thickness direction (Z direction), and the transmittance decreases as the incident angle increases, resulting in a state where the transmittance is low for light incident at a large angle obliquely to the thickness direction. In this embodiment, this state of the switchable layer 30 is called a light-transmitting state. In this embodiment, a large incident angle is an incident angle of 40° or more.

[0043] By providing such a light-controlling layer 30, the following effects can be achieved. When the light-controlling layer 30 is in the light-blocking state, the light-controlling layer 30 absorbs a large amount of light regardless of the incident angle, resulting in a black screen. Therefore, when the light-controlling layer 30 is in the light-blocking state and image light is projected from the image source LS onto the screen 70, the black luminance of the image can be reduced and the contrast of the image can be significantly improved. Furthermore, if the screen 70 does not have a dimming layer 30, the image light that passes through the reflective layer 13 may be totally reflected at the air interface on the back side of the screen 70 and exit from the surface on the image source side, which may result in image blurring such as double images. However, the screen 70 can absorb the image light that causes such double images by using the dimming layer 30, thereby significantly suppressing image blurring such as double images and enabling the display of clear images. Furthermore, the light control layer 30 absorbs the image light that passes through the reflective layer 13 and travels upward on the rear side of the screen 70, so that reflection of the image on the ceiling on the rear side of the screen 70 can be significantly reduced.

[0044] Next, when the light-controlling layer 30 is in a light-transmitting state, the light-controlling layer 30 can absorb a large amount of external light, such as sunlight or illumination light, incident from above the rear side of the screen 70, while ensuring sufficient transparency of the screen 70 in the front direction of the screen 70. Therefore, the light-controlling layer 30 can suppress haze on the screen caused by external light, thereby improving the transparency of the screen 70. When the image light is projected with the light-controlling layer 30 in the light-transmitting state, most of the external light incident at a large angle of incidence from the upper back side of the screen 70 is absorbed by the light-controlling layer 30, thereby improving the contrast of the image compared to a screen that does not have the light-controlling layer 30. In addition, although the effects of suppressing image blur and reflection of the image on the ceiling as described above are reduced compared to when the light-blocking state, they can still be expected.

[0045] As described above, the screen 70 of this embodiment does not have a light diffusion layer containing a diffusing material such as particles that have the effect of diffusing light, and the light is diffused and reflected by the fine unevenness of the surface of the reflective layer 13.

[0046] The light-switching layer 30 of this embodiment will be further described. This switchable layer 30 is normally dark, and in a light-transmitting state (when an electric field is applied), as described above, the transmittance of light at an incident angle of 0° is maximum, and the transmittance decreases as the incident angle increases. In contrast, a colored layer, which is a general light-absorbing layer that contains a coloring material or the like that has light-absorbing properties and absorbs part of the incident light and transmits part of it, has a small decrease in the transmittance of light incident from an oblique direction compared to the front transmittance (the transmittance of light that enters at an incident angle of 0 and exits at an exit angle of 0°).

[0047] FIG. 5 is a diagram illustrating a method for measuring the change in transmittance depending on the angle of incidence in Samples 1 to 3. As shown in Figure 5, Sample 1, which corresponds to the photochromic layer 30 of this embodiment, and Sample 2, which corresponds to the colored layer of the comparative example, were laminated on a plate-shaped member (acrylic plate) E1 made of a highly light-transmitting acrylic resin in a darkroom environment. Light was irradiated from a measurement light source E2 at a predetermined incident angle θ1 from the acrylic plate E1 side. A photodetector E3 (an MCPD6800 spectrometer manufactured by Otsuka Electronics Co., Ltd.) was then positioned in the direction of the exit angle θ1 on the sample side. The transmittance of the exit light in the direction of the exit angle θ1 was measured, and the reduction in the transmittance of light incident from an oblique direction relative to the front transmittance (the transmittance of light at an incident angle of 0° in the direction of the exit angle 0°) was calculated. In this measurement, Sample 1, which corresponds to the photochromic layer 30, was in a light-transmitting state with a voltage applied.

[0048] Sample 1 corresponds to an example of the light-controlling layer 30 of this embodiment and has a thickness of 0.26 mm. In Sample 1, the substrates 31A and 31B are PET resin films having a thickness of 0.125 mm, and the transparent electrodes 32A and 32B are formed of ITO. The liquid crystal layer 36 is formed of a guest-host liquid crystal composition using a dichroic dye composition. Sample 1 has a front transmittance of 29% in the light-transmitting state. Sample 2 is a sheet-like member made of acrylic resin containing a coloring agent, and has a thickness of 1 mm. Sample 2 has a front transmittance of 2.3%. Sample 3 is a normally white LCD panel having a liquid crystal layer driven by the TN method, and is equipped with a liquid crystal layer, transparent electrodes, a substrate, etc. similar to the dimming layer 30 of the present application, but further equipped with polarizing plates (not shown) on the image source side and the back side, respectively. The LCD panel of Sample 3 is a horizontally elongated rectangle, and is laminated on Member E1 so that the side view is parallel to the long side when measuring the transmittance as shown in Figure 5. When the panel surface of Sample 3 is viewed from the front, the transmission axis of the polarizing plate (not shown) forms a 45° angle with the vertical direction (short side direction) of the panel surface, and the front transmittance in the light-transmitting state is 0.75%. Sample 3 also has a thickness of 1.6 mm.

[0049] Fig. 6 is a graph showing the reduction rate of transmittance for obliquely incident light relative to the front transmittance for Samples 1 to 3. The vertical axis represents the reduction rate (%) of transmittance for light incident from an oblique direction relative to the front transmittance (transmittance in the direction of an exit angle of 0° for light at an incident angle of 0°), and the horizontal axis represents the incident angle (°). Fig. 6 shows the reduction rate for incident angles of 40° or more and 80° or less.

[0050] [Table 1]

[0051] Table 1 shows the rate of decrease in transmittance of obliquely incident light relative to the front transmittance for each incident angle for Samples 1 to 3. As shown in FIG. 6 and Table 1, in Sample 2, which corresponds to a light absorbing layer as a comparative example, the reduction rate at an incident angle of 40° was 50.4%, at an incident angle of 50° was 59.9%, at an incident angle of 60° was 76.1%, at an incident angle of 70° was 87.6%, and at an incident angle of 80° was 89.3%.

[0052] Furthermore, Sample 3, which is a comparative example, had a larger reduction rate than Sample 2, with a reduction rate of 58.5% at an incident angle of 40°, 72.8% at an incident angle of 50°, 84.6% at an incident angle of 60°, 94.4% at an incident angle of 70°, and 97.3% at an incident angle of 80°.

[0053] In contrast, for Sample 1, which corresponds to an example of the switchable layer 30 of this embodiment, the reduction rate at an incident angle of 40° was 71.7%, the reduction rate at an incident angle of 50° was 81.1%, the reduction rate at an incident angle of 60° was 90.5%, the reduction rate at an incident angle of 70° was 95.6%, and the reduction rate at an incident angle of 80° was 96.8%, and the reduction rate was greater than Samples 2 and 3 within the incident angle range of 40° to 80°. In particular, the reduction rates of transmittance at incident angles of 40° and 50° were approximately 21% greater for Sample 1 than for Sample 2. Furthermore, the reduction rate of transmittance at an incident angle of 40° for Sample 1 was 13.2% greater than for Sample 3, and the reduction rate of transmittance at an incident angle of 50° was 8.3% greater than for Sample 3. From the above, when the dimming layer 30 of this embodiment is in a translucent state, the screen 70 having the dimming layer 30 can transmit light from the front direction while effectively absorbing and blocking incident light from oblique directions (especially light with an incident angle of 40° or more).

[0054] Fig. 7 is a diagram showing an example of image light and external light incident on the screen 70 of the first embodiment. Fig. 7 shows an enlarged portion of a cross section similar to the cross section of the screen 70 shown in Fig. 2. For ease of understanding, Fig. 7 shows the screen as if there is no difference in refractive index between the layers. Image light L71 projected from an image source LS located below the screen 70 passes through the first base material layer 11 and enters the first optical shape layer 12. Then, image light L72, which is a part of the image light L71, is diffusely reflected by the reflective layer 13 of the first slope 121a of the unit optical shape 121, and is emitted toward the image source side (+Z side) and reaches the viewer O1 side. The image light L72 is diffusely reflected by the reflective layer 13, and the screen 70 can display an image with a sufficient viewing angle.

[0055] Since the image light L71 is projected from below the screen 70 and the angle β (see Figure 2) is larger than the angle of incidence of the image light L71 at each point in the vertical direction (Y direction) of the screen 70, the image light L71 does not directly enter the second inclined surface 121b, and the second inclined surface 121b does not contribute to the reflection of the image light. Furthermore, a portion of the image light L71, image light L73, passes through the reflective layer 13 toward the rear surface side, passes through the second optical shape layer 14 and the like toward the upper rear surface side, and is incident on the light-controlling layer 30. As described above, whether the light-controlling layer 30 is in a light-blocking state or a light-transmitting state, light such as this image light L73 that is incident on the light-controlling layer 30 at a large angle of incidence is absorbed by the liquid crystal layer 36 of the light-controlling layer 30. If such image light L73 reaches the ceiling on the rear side, it can cause the image to be reflected on the ceiling. However, in the screen 70 of this embodiment, the image light L73 is absorbed by the light control layer 30, so that the reflection of the image on the ceiling can be significantly reduced.

[0056] Furthermore, as described above, when the light-controlling layer 30 is in a light-blocking state, the light-controlling layer 30 absorbs most of the incident light, regardless of the angle of incidence onto the light-controlling layer 30. Therefore, when the light-controlling layer 30 is not provided, image blurring such as double images caused by the image light L73 being totally reflected at the air interface on the rear side of the screen and emitted toward the image source can be significantly suppressed, and a clear image can be displayed. Furthermore, the image light L73 can be prevented from being displayed as a left-right inverted image on the rear side of the screen 70. Furthermore, when the photochromic layer 30 is in a light-transmitting state, the photochromic layer 30 absorbs most of the light having a large incident angle, that is, light having an incident angle of 40° or more. Therefore, most of the light of the image light L73 having an incident angle of 40° or more with respect to the photochromic layer 30 is absorbed by the photochromic layer 30. Therefore, even when the photochromic layer 30 is in a light-transmitting state, the effect of reducing image blur such as double images as described above can be obtained, but the effect is more pronounced when the photochromic layer 30 is in a light-blocking state.

[0057] Next, we will explain external light such as sunlight and illumination light other than image light that enters the screen 70 from the back side (-Z side) or the image source side (+Z side), separately for when the dimming layer 30 is in a light-blocking state and when it is in a light-transmitting state. When the light-blocking layer 30 is in a light-shielding state, the light-blocking layer 30 absorbs most of the incident light, regardless of the angle of incidence on the light-blocking layer 30. Therefore, most of the external light G71 and G72 incident at a small angle on the screen 70, the external light G75 incident at a large angle on the screen 70 from above the image source side and transmitted through the reflective layer 13, and the external light G76 incident at a large angle on the screen 70 from above the rear side are absorbed by the light-blocking layer 30, and the observers O1 and O2 observe the light-blocking layer 30 (screen 40) as a black screen. Therefore, by projecting the image light L71 when the light-controlling layer 30 is in the light-blocking state, it is possible to display a good image with low black luminance and high contrast.

[0058] When the light-transmitting layer 30 is in a light-transmitting state, most of the external light G71, G72 incident at a small angle on the screen 70 is transmitted through the light-transmitting layer 30 without being absorbed by the light-transmitting layer 30, as shown in Fig. 7. Furthermore, since the screen 70 does not include a layer (light diffusion layer) containing a diffusing material such as particles that diffuse light, and the reflective layer 13 does not diffuse transmitted light, such external light G71, G72 is transmitted through the screen 70 without being diffused and is emitted toward the back side and the image source side, respectively.

[0059] Next, of the external light G73 incident on the screen 70 from above on the image source side, a portion of the external light (not shown) is reflected by the surface of the screen 70 but travels downward on the screen and does not reach the observers O1 and O2. Most of the external light G73 enters the screen 70, while a portion of the external light G74 is reflected by the reflective layer 13 and travels downward on the image source side of the screen 70, and exits downward on the image source side of the screen 70, or is totally reflected by the surface of the screen 70 on the image source side and travels downward again inside the screen 70, where it is attenuated. Some of the external light G73, external light G75, passes through the reflective layer 13 and travels downward on the rear side of the screen 70, and enters the photochromic layer 30. When the photochromic layer 30 is in a light-transmitting state, much of the external light 75 that is incident on the photochromic layer 30 at a large incident angle (an incident angle of 40° or more) is absorbed by the photochromic layer 30.

[0060] External light G76 incident on the screen 70 from above on the rear side is incident on the light-controlling layer 30 at a large angle of incidence. As described above, when the light-controlling layer 30 is in a light-transmitting state, the light-controlling layer 30 absorbs much of the light incident at a large angle of incidence (an angle of incidence of 40° or more), and most of the light is absorbed by the light-controlling layer 30. Note that part of the external light G76 is reflected by the surface on the rear side of the light-controlling layer 30, but travels downward on the rear side of the screen and does not reach the observers O1 and O2.

[0061] Therefore, when the dimming layer 30 is in a light-transmitting state, the screen 70 can suppress haze and other problems caused by external light entering from above the image source side or the back side, and when observers O1 and O2 positioned directly in front of the image source side and back side of the screen 70 observe the scenery on the other side of the screen 70 through the screen 70, the scenery on the other side of the screen 70 can be observed without being blurred or appearing white, and the screen 70 can exhibit high transparency. Furthermore, if image light is projected with the light-controlling layer 30 in a light-transmitting state, the transparency of the screen 70 can be maintained while preventing a decrease in image contrast due to external light.

[0062] In conventional reflective screens equipped with a light diffusion layer containing a diffusing material such as particles that diffuse light, the image light is diffused by the light diffusion layer twice, once before and after reflection from the reflective layer, in addition to being diffusely reflected by the reflective layer, resulting in excessive diffusion of the image light and blurring of the image (reduced resolution). In contrast, according to this embodiment, the image light is not diffused after being diffusely reflected by the reflective layer 13, so that a high-resolution image can be displayed.

[0063] Furthermore, in conventional reflective screens equipped with such a light diffusion layer, the light diffusion layer also diffuses unnecessary external light, resulting in reduced transparency as a screen and reduced contrast of images. In contrast, the screen 70 of this embodiment does not include such a light diffusion layer, and most of the external light passes through the screen without being diffused, is absorbed by the light control layer 30, or is emitted outside the range visible to the observers O1 and O2, thereby significantly suppressing a decrease in image contrast due to the diffusion of external light. Furthermore, when the light control layer 30 is in a light-transmitting state, the transparency of the screen 70 can also be maintained.

[0064] As described above, this embodiment can suppress blurring of the image (reduction in resolution) and display a clear image. Furthermore, this embodiment can suppress the reflection of the image on the ceiling or the like due to the image light transmitted through the reflective layer, and the double image caused by such image light being totally reflected on the rear surface of the screen and emitted toward the image source. Furthermore, according to this embodiment, unnecessary external light is diffused and does not reach the viewer, so that high-contrast images can be displayed, and when the dimming layer 30 is in a translucent state, a highly transparent screen can be obtained. Furthermore, according to this embodiment, the light-control layer 30 can be appropriately selected to be in a light-transmitting state or a light-blocking state depending on the image to be displayed and the environment in which the screen 70 is used, thereby improving convenience.

[0065] (Second embodiment) Fig. 8 is a diagram showing the layer structure of the screen 20 of the second embodiment. Fig. 8 shows an enlarged portion of a cross section that passes through the screen center (the geometric center of the screen) of the screen 20 (a point corresponding to point A shown in Fig. 1), is parallel to the vertical direction of the screen (Y direction), and is perpendicular to the screen surface (parallel to the Z direction). The screen 20 of this embodiment has the same configuration as the screen 70 of the first embodiment described above, except that it has a light control layer 16 on the image source side of the first base material layer 11 via a bonding layer 17a, and a second base material layer 25. Therefore, parts that perform similar functions as those in the first embodiment described above are given the same reference numerals or the same reference numerals with the same suffixes, and redundant explanations will be omitted as appropriate.

[0066] The screen 20 of the second embodiment is a reflective screen that displays an image by reflecting image light projected from an image source LS, similar to the screen 70 of the first embodiment. The screen 20 of the second embodiment is used in the image display device 7 in place of the screen 70. In its thickness direction (Z direction), the screen 20 has, from the image source side, a light control layer 16, a bonding layer 17a, a first base material layer 11, a first optical shape layer 12, a reflective layer 13, a second optical shape layer 14, a second base material layer 25, a bonding layer 17c, and a dimming layer 30.

[0067] The bonding layer 17a is a layer that functions to integrally bond the light control layer 16 and the first base material layer 11. The bonding layer 17a can be made of an adhesive or sticky material that has high light transparency. In this embodiment, the combined thickness of the bonding layer 17a and the first base layer 11, i.e., the distance D1 from the rear surface (-Z side) of the light control layer 16 to the image source surface (+Z side) of the first optical shape layer 12 in the thickness direction (Z direction) of the screen 20, is preferably 0.5 mm or less. If the magnitude of this distance D1 is greater than 0.5 mm, the distance between the light control layer 16, which has a diffusing effect described below, and the reflective layer 13 becomes too large, resulting in increased image blurring and reduced image clarity. Therefore, when image clarity is important, the distance D1 is preferably within the above range.

[0068] The light control layer 16 is a layer located closer to the image source side (+Z side) than the first base material layer 11 in the thickness direction, and has the function of diffusing and transmitting light incident from a specific angular range, and transmitting light incident from other angular ranges without diffusing it. The light control layer 16 is provided integrally with the first base material layer 11 on the image source side (+Z side) via a bonding layer 17a. Fig. 9 is a diagram illustrating the light control effect of the light control layer 16. Fig. 9 shows a cross section parallel to the vertical direction (Y direction) of the screen and the thickness direction (Z direction) of the light control layer 16. In Fig. 8, the image source side (+Z side) and rear side (-Z side) surfaces of the light control layer 16 are parallel to the screen surface (XY plane), and the dashed line H is a line perpendicular to the image source side surface and rear side surface of the light control layer 16.

[0069] In the cross section shown in Figure 9, the light control layer 16 has the function of diffusing light that is incident from the air on the image source side (+Z side) at an incident angle within the first incident angle range R1 and emitting it to the back side (-Z side), and transmitting light that is incident at an incident angle within the second incident angle range R2, which is an incident angle other than the first incident angle range R1, to the back side without diffusing it. In addition, in the cross section shown in Figure 9, the light control layer 16 has the function of diffusing light that is incident from the air on the back side (-Z side) at an incident angle within the third incident angle range R3 and emitting it toward the image source side (+Z side), and transmitting light that is incident at an incident angle within the fourth incident angle range R4, which is an incident angle other than the third incident angle range R3, toward the image source side without diffusing it.

[0070] The first incident angle range R1 includes the main incident angle range of the image light L0 that is projected from the image source LS and enters the screen 20 (light control layer 16). The first incident angle range R1 is a range on the image source side (+Z side) that is between 25° and 55° downward (-Y side) with respect to the straight line H. In this case, the light control layer 16 diffuses light that is incident on any point on the surface on the image source side from the lower side in the vertical direction of the screen at an incident angle of between 25° and 55° and outputs it to the back side (-Z side). The second incident angle range R2 is an angle other than the first incident angle range R1 on the image source side of the light control layer 16.

[0071] The third incident angle range R3 is a range on the rear side (-Z side) that is 25° or more and 55° or less upward (+Y side) with respect to the straight line H. In this case, the light control layer 16 diffuses light that is incident on any point on its rear side surface from the upper side in the vertical direction of the screen at an incident angle of 25° or more and 55° or less, and outputs the light to the image source side (+Z side). The fourth incident angle range R4 is an angle on the rear surface side of the light control layer 16 other than the third incident angle range R3.

[0072] Therefore, at any point on the surface on the image source side, the light control layer 16 diffuses and transmits light that is incident from the bottom side in the vertical direction of the screen at an incident angle of 25° to 55° and transmits light that is incident from any other angle range without diffusing it.Furthermore, at any point on the surface on the rear side, the light control layer 16 diffuses and transmits light that is incident from the top side in the vertical direction of the screen at an incident angle of 25° to 55° and transmits light that is incident from any other angle range without diffusing it.

[0073] The haze value (diffuse transmittance) of light that is incident on the light control layer 16 from the image source side at an incident angle within the first incident angle range R1 and exits to the back side is preferably 80% or more. The haze value of light that is incident on the light control layer 16 from the back side at an incident angle within the third incident angle range R3 and exits to the image source side is also preferably similar. The haze value is expressed as the ratio of the diffuse transmittance to the total light transmittance, and means the diffusion rate of transmitted light. The haze value of the light control layer 16 can be measured using a haze meter (for example, HM-150 manufactured by Murakami Color Research Laboratory).

[0074] For incident light within the first incident angle range R1 and the third incident angle range R3, since the first incident angle range R1 and the third incident angle range R3 in this embodiment are 25° or more and 55° or less, the assumed incident angle is set to 40°, and the transmittance when light is incident at this angle is defined as the total light transmittance, and the proportion of light that is diffused by 2.5° or more to the light that is incident at this assumed incident angle, travels straight through the light control layer 16, and is transmitted and emitted is defined as the diffuse transmittance.

[0075] On the other hand, the haze value (diffuse transmittance) of light incident on the light control layer 16 from the image source side at an incident angle within the second incident angle range R2, particularly light incident at an incident angle of 0° and exiting from the rear side, is preferably low, ideally 0%. The haze value of light incident on the light control layer 16 at an incident angle within the fourth incident angle range R4 is also preferably similar.

[0076] A suitable example of such a light control layer 16 is a field of view control film (for example, field of view control film Y-2555 manufactured by Lintec Corporation) formed by laminating multiple layers of transparent resin with different refractive indices in a predetermined direction at a predetermined thickness, and changing the direction of ultraviolet light irradiation when curing each layer.

[0077] As described above, the screen 20 of this embodiment does not have a light diffusion layer containing a diffusing material such as particles that have the effect of diffusing light, and only light that enters the light control layer 16 at an incident angle within a specific angle range (first incident angle range R1 and third incident angle range R3) is diffused, and further diffused and reflected by the fine uneven shape of the surface of the reflective layer 13.

[0078] The second base layer 25 of this embodiment is thick and has sufficient rigidity to maintain the flatness of the screen surface of the screen 20. Therefore, the screen 20 can sufficiently maintain the flatness of the screen surface without being joined to a support plate (not shown) or the like shown in the first embodiment. However, this is not limiting, and in order to further improve the flatness of the screen, a form in which the aforementioned support plate is joined may also be used. The second base layer 25 is preferably a plate-like member formed of, for example, a highly transparent acrylic resin, polycarbonate resin, glass, etc. The thickness of the second base layer 25 is preferably 3 to 8 mm, and the thickness can be selected appropriately depending on the screen size of the screen 20. In this embodiment, the screen 20 is shown as having the second base layer 25, but this is not limited to this. The screen 20 may have the second base layer 15 as in the first embodiment, and may have a thick, translucent substrate layer (not shown) on the back side thereof.

[0079] Furthermore, since the screen 20 of this embodiment includes the second base material layer 25 as described above, in its thickness direction (Z direction), the distance D2 from the image source side (+Z side) surface of the light control layer 30 to the back side (-Z side) surface of the second optical shape layer 14 is greater than the distance D1 from the back side (-Z side) surface of the light control layer 16 to the image source side (+Z side) surface of the first optical shape layer 12. In other words, the shortest distance from the image source side (+Z side) surface of the light control layer 30 to the reflective layer 13 is greater than the shortest distance from the back side (-Z side) surface of the light control layer 16 to the reflective layer 13. This makes it possible to reduce the distance D1 while improving the flatness of the screen surface of the screen 20. Therefore, the distance from the light control layer 16 to the reflective layer 13 can also be reduced, so that image light that is incident on the light control layer 16 at an incident angle within the first incident angle range R1 is diffused by the light control layer 16 and spreads within the screen 20, thereby reducing image blur such as double images that occurs when the position where the light is reflected by the reflective layer 13 is separated.

[0080] Fig. 10 is a diagram showing an example of image light and external light incident on the screen 20 of the second embodiment. Fig. 10 shows an enlarged portion of a cross section similar to the cross section of the screen 70 shown in Fig. 2. In addition, for ease of understanding, Fig. 10 shows the structure as if there is no difference in refractive index between the layers. Image light L21 projected from an image source LS located below the screen 20 is incident on the light control layer 16 at an incident angle within the first incident angle range R1 and diffused, then passes through the bonding layer 17a and the first base material layer 11 and enters the first optical shape layer 12. Then, image light L22, which is a part of the image light L21, is diffusely reflected by the reflective layer 13 on the first slope 121a of the unit optical shape 121 and exits toward the image source side (+Z side). At this time, in the cross section of the screen 20 shown in FIG. 10 , the image light L21 is incident on the light control layer 16 from the back side at an angle corresponding to an incident angle in the fourth incident angle range R4 (particularly, an incident angle of 0° and near 0°), and therefore is not diffused by the light control layer 16 and exits toward the image source side to reach the viewer O1 side.

[0081] As described above, the image light L22 is incident on the light control layer 16 within the first incident angle range R1 and is diffusely reflected by the reflective layer 13. This allows the image light L22 to be suitably diffused, and the screen 20 can display an image at a sufficient viewing angle. Furthermore, the image light L22 is diffused by the light control layer 16 when it enters the screen 20, and is then diffusely reflected by the reflective layer 13, so that it is diffused twice at different positions in the thickness direction of the screen 20. This enables the screen 20 to reduce glare (speckle) in the image and suppress image blur (decrease in resolution) caused by excessive diffusion.

[0082] Furthermore, a portion of the image light L21, image light L23, passes through the reflective layer 13 toward the rear side, passes through the second optical shape layer 14, and is obliquely incident on the image source side surface of the light control layer 30. Most of this image light L23 is absorbed by the light control layer 30 whether the light control layer 30 is in a light-transmitting state or a light-blocking state. Therefore, such image light L23 does not cause an image to be displayed on the rear side, and reflection of the image on the ceiling, etc., can be suppressed.

[0083] Next, external light such as sunlight or illumination light other than image light that enters the screen 20 from the rear side (-Z side) or the image source side (+Z side) will be described. Furthermore, when the dimming layer 30 is in a light-blocking state, as in the first embodiment, much of the external light G21, G22 having a small angle of incidence on the screen 20, the external light G25 that enters the screen 20 from above on the image source side at a large angle of incidence and passes through the reflective layer 13, and the external light G26 that enters the screen 20 from above on the back side at a large angle of incidence are absorbed by the dimming layer 30, and the dimming layer 30 (screen 20) is observed as a black screen by the observers O1 and O2. Therefore, by projecting the image light L21 with the light-blocking layer 30 in a light-blocking state, it is possible to display a good image with low black luminance and high contrast.

[0084] When the light-transmitting layer 30 is in a light-transmitting state, most of the external light G21 and G22 incident at a small angle on the screen 20 is transmitted through the light-transmitting layer 30 without being absorbed by the light-transmitting layer 30, as shown in Fig. 10. Furthermore, the screen 20 does not include a layer (light diffusion layer) containing a diffusing material such as particles that diffuse light, and the reflective layer 13 does not diffuse transmitted light. The external light G21 is incident on the light control layer 16 from the image source side at an incident angle within the second incident angle range R2, and the external light G22 is incident on the light control layer 16 from the back side at an incident angle corresponding to an angle within the fourth incident angle range R4. Therefore, as shown in Fig. 10, such external light G21 and G22 are transmitted through the screen 20 without being diffused and are emitted toward the back side and the image source side, respectively.

[0085] Of the external light G23 incident on the screen 20 from above on the image source side, a portion of the external light (not shown) is reflected by the surface of the screen 40 but travels downward toward the screen and does not reach the observers O1 and O2. Most of the external light G23 is incident on the light control layer 16 from the image source side at an incident angle within the second incident angle range R2, and therefore passes through the light control layer 16 without being diffused and travels within the screen 20 toward the rear side. Some of the external light G23, external light G24, is reflected by the reflective layer 13 and travels downward toward the image source side of the screen 20, and then exits downward toward the image source side of the screen 20, or is totally reflected by the surface of the screen 20 on the image source side and travels downward again inside the screen 20, where it is attenuated. Some of the external light G23, external light G25, travels downward toward the rear side of the screen 20 and enters the light control layer 30. As described above, when the switchable layer 30 is in the light-transmitting state, the switchable layer 30 absorbs most of the light incident at a large angle.

[0086] Like the external light G76 in the first embodiment, part of the external light G26 incident on the screen 20 from above on the rear side is reflected by the surface on the rear side of the light control layer 30 and travels downward on the rear side of the screen, and therefore does not reach the observers O1 and O2. Also, like the external light G76 in the first embodiment, most of the external light G26 is absorbed by the liquid crystal layer 36 of the light control layer 30.

[0087] Therefore, when the dimming layer 30 is in a light-transmitting state, the screen 20 can suppress haze and other problems caused by external light entering from above the image source side or the back side, and when observers O1 and O2 positioned directly in front of the image source side and back side of the screen 20 observe the scenery on the other side of the screen 20 through the screen 20, the scenery on the other side of the screen 20 can be observed without being blurred or appearing white, and the screen 20 can exhibit high transparency. Furthermore, if image light is projected with the light-controlling layer 30 in a light-transmitting state, the transparency of the screen 20 can be maintained while suppressing a decrease in contrast due to external light and reducing glare in the image.

[0088] As described above, according to this embodiment, similar to the first embodiment, image blurring such as double images can be reduced, and clear, high-contrast images can be displayed. In particular, when image light is projected with the light-blocking layer 30 in a light-blocking state, excellent images with high contrast can be displayed. Furthermore, in a conventional reflective screen that has a light diffusion layer containing a diffusing material such as particles that diffuse light at a position corresponding to the light control layer 16 of the screen 20 of this embodiment, the image light is diffused by the light diffusion layer twice, before and after reflection at the reflective layer, in addition to being diffusely reflected at the reflective layer, resulting in excessive diffusion of the image light and blurring of the image (reduced resolution). In contrast, according to this embodiment, the image light is not diffused after being diffusely reflected by the reflective layer 13, so that a high-resolution image can be displayed. Furthermore, according to this embodiment, the image light transmitted through the reflective layer 13 is reflected on the ceiling or the like on the rear side, and the reflection of the image on the ceiling can be suppressed.

[0089] (Third embodiment) Fig. 11 is a diagram showing the layer structure of the screen 40 of the third embodiment. Fig. 11 shows an enlarged portion of a cross section that passes through the center of the screen (the geometric center of the screen) of the screen 40, is parallel to the vertical direction of the screen (Y direction), and is perpendicular to the screen surface (parallel to the Z direction). The screen 40 of this embodiment has a similar configuration to the screen 70 of the first embodiment described above, except that it has a translucent substrate layer 48 on the image source side of the first base layer 11 via a bonding layer 17b, and further has the bonding layer 17a and light control layer 16 shown in the second embodiment on the image source side. Therefore, parts that perform similar functions as those in the first and second embodiments described above are given the same reference numerals or the same reference numerals with the same suffixes, and redundant explanations will be omitted as appropriate.

[0090] The screen 40 of the third embodiment is a reflective screen that displays an image by reflecting image light projected from an image source LS, similar to the screen 70 of the first embodiment. This screen 40 is used in the image display device 7 in place of the screen 70 of the first embodiment. As shown in Figure 10, the screen 40 has, in the thickness direction (Z direction), a light control layer 16, a bonding layer 17a, a translucent substrate layer 48, a bonding layer 17b, a first base material layer 11, a first optical shape layer 12, a reflective layer 13, a second optical shape layer 14, a second base material layer 15, a bonding layer 17c, a dimming layer 30, etc., in that order from the image source side (+Z side).

[0091] The bonding layer 17b is a layer that functions to integrally bond the light-transmitting substrate layer 48 and the first base material layer 11. The bonding layer 17b can be made of an adhesive or sticky material that has high light transparency. The light-transmitting substrate layer 48 is a plate-like member with high light transmittance. The light-transmitting substrate layer 48 is thicker than the first base material layer 11, the second base material layer 15, etc., and has enough rigidity to maintain the flatness of the screen surface of the screen 40. The light-transmitting substrate layer 48 is provided on the image source side of the first base material layer 11 via the bonding layer 17b. Such a light-transmitting substrate layer 48 is preferably formed from a highly light-transmitting material such as acrylic resin, polycarbonate resin, or glass. From the viewpoint of maintaining sufficient flatness of the screen surface, the light-transmitting substrate layer 48 preferably has a thickness of 3 mm to 8 mm. The thickness of this light-transmitting substrate layer 48 is selected according to the screen size and other factors, and so as to satisfy the preferred range of the distance D1 in this embodiment, which will be described later. In order to further improve the flatness of the screen, the screen 40 may be used with a support plate, as shown in the first embodiment, laminated on the rear side.

[0092] The screen 40 of this embodiment includes the above-described light-transmitting substrate layer 48, and therefore in its thickness direction (Z direction), a distance D1 from the rear surface (-Z side) of the light control layer 16 to the image source side (+Z side) surface of the first optical shape layer 12 is greater than a distance D2 from the image source side surface of the light control layer 30 to the rear surface of the second optical shape layer 14. In other words, the shortest distance from the rear surface of the light control layer 16 to the reflective layer 13 is greater than the shortest distance from the image source side surface of the light control layer 30 to the reflective layer 13. This ensures a sufficient distance D1 while improving the flatness of the screen 40. Therefore, the distance between the light control layer 16, which has a diffusing effect, and the reflective layer 13, which diffuses light, can be sufficiently increased, further enhancing the effect of reducing glare (speckle) in the image. Note that, in order to enhance the effect of reducing glare in the image while maintaining the clarity of the image, the distance D1 is preferably greater than 0.5 mm and equal to or less than 8 mm.

[0093] As described above, according to this embodiment, the screen 40 can display a clear image with high contrast and suppressed image blur such as double images, similar to the first embodiment. In particular, when the image light is projected with the light-blocking layer 30 in the light-blocking state, an excellent image with high contrast can be displayed. Furthermore, according to this embodiment, as in the second embodiment described above, the image light is diffused twice at different positions in the thickness direction (Z direction) of the screen 40, so that the screen 40 can reduce glare (speckle) in the image and suppress image blur (reduced resolution) due to excessive diffusion.

[0094] Furthermore, according to this embodiment, the screen 40 has a light-transmitting substrate layer 48, and the distance D1 is sufficiently secured, so that the distance between the light control layer 16 having a diffusing effect and the reflective surface that diffuses and reflects can be sufficiently widened, and the effect of reducing glare (speckle) in the image can be further enhanced. Furthermore, according to this embodiment, the image light is diffused by the light control layer 16, and then diffusely reflected by the reflective layer 13, after which it is not diffused again, so that an image with high resolution can be displayed. Furthermore, according to this embodiment, the image light transmitted through the reflective layer 13 is reflected on the ceiling or the like on the rear side, and the reflection of the image light on the ceiling can be suppressed.

[0095] (Fourth embodiment) Fig. 12 is a diagram showing the layer structure of the screen 80 of the fourth embodiment. Fig. 12 shows an enlarged portion of a cross section that passes through the center of the screen (the geometric center of the screen) of the screen 80, is parallel to the vertical direction of the screen (Y direction), and is perpendicular to the screen surface (parallel to the Z direction). The screen 80 of this embodiment has the same configuration as the screen 70 of the first embodiment described above, except that translucent substrate layers 88 and 89 are laminated on the image source side of the base material 31A of the dimming layer 30 and the back side of the base material 31B via bonding layers 87a and 87b. Therefore, parts that perform similar functions as those in the first embodiment described above are given the same reference numerals or the same reference numerals with the same suffixes, and redundant explanations will be omitted as appropriate.

[0096] The screen 80 of the fourth embodiment is a reflective screen that displays an image by reflecting image light projected from an image source LS, similar to the screen 70 of the first embodiment. This screen 80 is used in the image display device 7 in place of the screen 70 of the first embodiment. As shown in Figure 12, the screen 80 has, in the thickness direction (Z direction), in order from its image source side (+Z side), a first base material layer 11, a first optical shape layer 12, a reflective layer 13, a second optical shape layer 14, a second base material layer 15, a bonding layer 17c, a translucent substrate layer 88, a bonding layer 87a, a dimming layer 30, a bonding layer 87b, a translucent substrate layer 89, etc.

[0097] The light-transmitting substrate layers 88, 89 are plate-like members that have high light transmittance and are thicker than the first base material layer 11, the second base material layer 15, etc. These light-transmitting substrate layers 88, 89 are preferably made of float glass or tempered glass depending on the required strength. Furthermore, the light-transmitting substrate layers 88, 89 preferably have a thickness of 0.5 mm or more and 8 mm or less. The light-transmitting substrate layer 88 is laminated on the image source side of the base material 31A via a bonding layer 87a, and the light-transmitting substrate layer 89 is laminated on the back surface side of the base material 31B via a bonding layer 87b. The bonding layers 87a and 87b may be made of an adhesive or sticky material with high optical transparency, a sheet-like member with optical transparency and adhesiveness, etc. Alternatively, the bonding layers 87a and 87b may be made of an intermediate film-forming sheet made of polyvinyl butyral resin (PVB resin), etc. 12, in this embodiment, the light-modulating layer 30 is sandwiched between two light-transmitting substrate layers 88 and 89 via bonding layers 87a and 87b. Note that the light-transmitting substrate layers 88 and 89 may be larger than the light-modulating layer 30 when viewed in the thickness direction of the screen 80, and the bonding layers 87a and 87b may fill the space from the outer edge of the light-modulating layer 30 to the ends of the light-transmitting substrate layers 88 and 89.

[0098] According to this embodiment, in addition to the effects shown in the first embodiment, the following effects can be achieved. According to this embodiment, the liquid crystal material of the liquid crystal layer 36 falls in the direction of gravity at high temperatures, causing unevenness in the distribution of the liquid crystal material, and this can reduce unevenness in the transmittance distribution when the dimming layer 30 is in a light-blocking state or a light-transmitting state. Furthermore, according to this embodiment, the two light-transmitting substrate layers 88 and 89 can improve the flatness of the screen surface of the screen 80. In this embodiment, the screen 80 is shown as not having a light control layer 16, but this is not limited to this, and the screen 80 may also be configured to have a light control layer 16 on the image source side of the first base layer 11 via a bonding layer 17a. In this embodiment, the screen 80 is shown as an example in which the dimming layer 30 is sandwiched between the translucent substrate layers 88 and 89, but this is not limited to this, and the screen 80 may also have a configuration in which one translucent substrate layer is laminated on the image source side or the back side of the dimming layer 30.

[0099] (Variations) The present invention is not limited to the above-described embodiments, and various modifications and variations are possible, and these are also within the scope of the present invention.

[0100] (1) In each embodiment, a hard coat layer for the purpose of preventing scratches may be provided on the image source side (+Z side) and rear side (-Z side) surfaces of the screens 70, 20, 40, and 80. The hard coat layer is formed, for example, by applying an ultraviolet curable resin (e.g., urethane acrylate) having hard coat function to the image source side and rear side surfaces of the screens 70, 20, 40, and 80.

[0101] Furthermore, instead of being limited to a hard coat layer, one or more layers having appropriate functions such as anti-reflection, ultraviolet absorbing, anti-fouling, anti-static, etc. may be selected and provided on the image source side and rear side surfaces of the screens 70, 20, 40, 80 depending on the usage environment and purpose of the screens 70, 20, 40, 80. Furthermore, in the second and third embodiments, a touch panel layer or the like may be provided on the image source side of the light control layer 16. In particular, when an anti-reflection layer is provided on the surface of the screen 70, 20, 40, 80 facing the image source, the reflection of image light on the surface of the screen 70, 20, 40, 80 is reduced, increasing the amount of light incident on the screen 70, 20, 40, 80, thereby improving the brightness of the image. In addition, it is possible to prevent the image light reflected by the reflective layer 13 from reflecting at the interface with the air on the image source side and emitting to the rear side, causing the image to appear as if it is leaking to the rear side. The layers having various functions, such as the hard coat layer, may be provided on either the image source side or the back side of the screens 70, 20, 40, 80.

[0102] (2) In each embodiment, the screens 70, 20, 40, and 80 have a first optical shape layer 12 in which unit optical shapes 121 are arranged, and the reflective layer 13 is formed along the unit optical shapes 121. However, this is not limited to this. For example, the rear surface of the first optical shape layer may be a flat, rough surface with fine, irregular concave and convex shapes, the reflective layer 13 may be formed on the flat surface, and the second optical shape layer may be formed on the rear surface.

[0103] (3) In the second and third embodiments, the light control layer 16 has been described as selectively diffusing incident light in a cross section parallel to the screen vertical direction and thickness direction, depending on the angle of incidence in the screen vertical direction. However, this is not limiting. The light control layer 16 may be configured to selectively diffuse incident light in a cross section parallel to the array direction and thickness direction of the unit optical shapes 121, depending on the angle of incidence in the array direction of the unit optical shapes 121. When the unit optical shapes 121 are arranged concentrically around point C as in the embodiment, the optical performance of the light control layer 16 also exhibits a characteristic of being distributed concentrically. This configuration allows for more effective light diffusion, ensuring a sufficient viewing angle in areas where the viewing angle is likely to be reduced, such as the upper left and right ends of the screen.

[0104] In the second and third embodiments, the light control layer 16 has a constant specific angle range for diffusing and transmitting incident light in a cross section parallel to the vertical direction and thickness direction of the screen, but the specific angle range may vary continuously or stepwise along the vertical direction of the screen. By using such a configuration, light can be diffused more effectively in response to the incident angle of image light that varies in the vertical direction of the screen, and a good image can be displayed.

[0105] (4) In the second and third embodiments, the light control layer 16 may be configured to transmit light incident from the rear side (-Z side) without diffusing it, regardless of the incident angle. That is, the light control layer 16 may be configured not to have the third incident angle range R3.

[0106] (5) In each embodiment, the screens 70, 20, 40, and 80 may include a colored layer that absorbs a portion of incident light and transmits a portion of the light, located closer to the image source (+Z side) than the reflective layer 13. This colored layer is colored with a dark colorant such as black or gray so as to have a predetermined transmittance. By providing such a colored layer closer to the image source than the reflective layer 13, the screens 70, 20, 40, and 80 can reduce the black luminance of the image and absorb external light from the image source side, thereby improving the contrast of the image. Such a colored layer may be provided, for example, at a position on the screen 70, 20, 40, 80 closest to the image source, or, for example, the first base layer 11, the bonding layer, the translucent substrate layer 48, etc. in each embodiment may contain a coloring material and have the function of the above-mentioned colored layer. Furthermore, it is particularly effective to place the colored layer on the screens 70, 20, 40, 80 closest to the image source, that is, at a position that forms an interface with the air on the image source side of the screens 70, 20, 40, 80.

[0107] (6) In each embodiment, the first inclined surface 121a and the second inclined surface 121b of the unit optical shape 121 may have, for example, a shape in which a curved surface and a flat surface are combined, or may have a bent surface shape. Furthermore, the unit optical shape 121 may be a polygonal shape formed by three or more surfaces. Furthermore, although the example in which the reflective layer 13 is formed on the first inclined surface 121a and the second inclined surface 121b has been shown, the present invention is not limited to this, and the reflective layer 13 may be formed on at least a part of the first inclined surface 121a, for example. Furthermore, in each embodiment, an example has been shown in which the first inclined surface 121a and the second inclined surface 121b have a fine and irregular uneven shape, but this is not limited thereto, and the first inclined surface 121a alone may have a fine and irregular uneven shape.

[0108] (7) In each embodiment, the video source LS is located at the center of the screen 70, 20, 40, 80 in the horizontal direction and below the screen, but this is not limiting and the video source LS may be located, for example, above the screen 70, 20, 40, 80. In this case, the screen 70, 20, 40, 80 has its top-to-bottom direction (Y direction) reversed. The image source LS may also be configured to project image light from an oblique direction onto the screens 70, 20, 40, and 80. In this case, point C, which is the Fresnel center of the circular Fresnel lens shape of the first optical shape layer 12, is positioned to match the position of the image source LS. By using such a configuration, the position of the image source LS can be freely set.

[0109] (8) In each embodiment, if the first optical shape layer 12 or the second optical shape layer 14 has sufficient thickness, rigidity, etc., it is possible to adopt a configuration in which at least one of the first base material layer 11 and the second base material layer 15 is not provided.

[0110] The present invention is not limited to the above-described embodiments, but may be combined with other embodiments as desired. [Explanation of symbols]

[0111] 7. Video display devices 70, 20, 40, 80 screen 11 First base layer 12 First optical shape layer 13 Reflective layer 14 Second optical shape layer 15,25 Second base layer 17a,17b,17c,17d Bonding layer 16 Light control layer 48,88,89 Transparent substrate layer 30 Photochromic Layer 31A,31B base material 32A,32B Transparent electrode 33A, 33B Alignment layer 36 Liquid crystal layer LS Image Source

Claims

[Claim 1] A reflective screen that displays an image by reflecting at least a portion of image light projected from an image source, a semi-transmissive reflective layer having a fine irregular uneven surface formed thereon, which diffusely reflects at least a portion of incident light by the uneven surface and transmits a portion of the incident light; a light control layer that is disposed on the rear side of the reflective layer in the thickness direction of the reflective screen and that absorbs a part of incident light and transmits a part of the light, thereby adjusting transmittance; Equipped with The optical element does not include a light diffusion layer containing particles that diffuse light. A reflective screen featuring:

Images